Tank cover



Sept. 7 1926. l

1 L. A. BALDWIN TANK COVER Filed July l5 1/7 a@ n', fr

, aff/f CX47 Patented Sept. 7, 1926.

UNITED STATES y l ,11,599,109 1 afrni-v1`V OFFICE.

LESLIE A. BALDWIN, OF UNIVERSITY CITY, MISSOURI, .ASSIGNOR TO JOHNS-MAN- VILLE, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TANK Govan.

Application led July 15, 1925. Serial No. 43,754.

My invention relates to covers for tanks in which volatile liquids such as petroleum, are

stored. In order to serve its purposes completely, the cover for vsuch a tank should be gas tight and weather-proof, capable of adapting itself to or of compensating for, the irregular and persistent expansion and contractions of the tank and its roof; .an effective heat insulator so as to minimize fluctuations of temperatures of the gases which collect by volatilization of constituents of the liquid inthe tank; and, to the same end, should have an upper exposed surface strongly reflective of heat so as to reduce the quantity of heat absorbed by the covering layers and transmitted to the interior of the tank.

The Weather-proofing of a tank cover must be 'of sheet-rooting with seams cemented by weather-resistant material; practically this requirement leaves no alternative and dictates the employiment of asphalt-treated or impregnated sheets of librovusy textile or felted material, (preferably the latter) in which the asphalt impregnant is the effective weather-proofing factor. This being the case, the importance of preventing access to the asphaltic material by the volatile constituents of petroleum and the like, which have a vigorous disintegrating effect on asphalt. becomes obvious. And, when the inevitable expansions and contractions of the roof and sides are taken into calculation, the difficulty of providing a vapor-proof layer or membrane which shallretain its integrity and effectively endure to forbid the percolation of asphalt-deteriorating vapors into the weather-proofingr asphaltic layer of a tank cover, becomes manifest.

The improvements in tank covers herein described are addressed to this situation.

Usually, a membrane or coating designed to oppose passage of a fluid is placed at the threshold--so to speak-of the passage to be barred. On the contrary, in the circumstances presented by the petroleum t'.nk and its environing conditions-I place a sealing layer or membrane (or both) in which ultimate reliance is reposed, as far as possible from the tank-roof and its volatile contents, taking the fullest available advantage of the cushioningr effect of the heat-insulating layers which forni part of the tank covering, and re airing them to perform a function other t an, or supplemental to, their heat 'whichharden and become brittle.

insulating function. Also, and by strong preference, I employ for the vapor sealing material a vapor resistant cement which is lo a substantial degree elastic at the temperatureI of its use, as well as plastic at higher temperatures, and liquetiable at higher temperatures still, aseonstrasted with materials For example, I have found by test and practice, that a composition like that of printers ink rolls (glue and glycerine, glue and molasses, glue. and glycerine with minor proportions of varnishes, ete.) is an elfective ccmentitious material for my purpose, either when laid as a cementitious coating, or used to iinpregnate a fibrous sheet such as paper and thus to form a vapor-,proof membrane. I

The elasticity of such a cement renders it useful and ell'ective to form an auxiliary protective layer or seal, either as a coating or a constituent of a membrane, in a level or stratum of the tank covering nearer lo the vapor content of the tank than the preferred outermost location above referred to;either between laminas of the heat insulating material, or directly on the tank roof. Since a maximuml of preventive measures against deterioration of the asphaltic Weatherproofingr material is Wholly to be desired, I prefer to employ this elastic, vapor-proof cementitions material both in the outermost stratum of the tank covering, inside the Weather# proofing,and, as a pr1mary vapor-seal, at a.

l rial reduces the demand for elasticity on the part of the/vapor sealing layer or membrane (or both) which is superposed on the heat insulatinpr layer. it is ne vcrtheless profe able to `have such vapor-proolin er layer possess elasticity as an element of insurance.

I have. alluded to the cushioning ell'ect of the heat-insulatingr layers in the tank cover. This effect or function.. invoked and availed of in the relationship with a vapor sealing layer supcrposed on the heat insulating material, is one which any true heabinsulator Will perform. The only real bruit-insulator known is gas (air) in a state of rest. Cellular. reticulated. or felt-ed bodies contain a multitude of air-filled spaces. each so small that '-convective currents therein are negli by a layer or pellicle of elasticvapor-prooi."

cement laid upon or close to the tank roof should under unusual stresses become fractured, these stresses will be in large measure absorbed by the cellular or porous heatinsulating portions otl the tank cover, and n the outer ultimate vapor sealing layer ot' similar elastic material, always in reserve against such emergency will have remained unbroken and iii-full capacity to perform its function of keeping tank vapors away from the asphalticweathenprooting material atV the top of the tank covering. j

While the cementitious material above named, viz, a compositionA of glue with glycerine, molasses, etc., is, by reason of its elasticity to be preferred over other vapor-proof, pellicle-forming materials, others may be effectively employed, especially When laid upon and cushioned by,- a heat insulating layer and thereby not sub'- 'ected to such stresses as must besustained y a vapor-proof, cementitious layer ap plied directly to the tank roof itself. A mong substitutes for the elastic cement specifically recommended, may be mentioned polymerized oils, blown or boiled drying oils, and even such materials as sodium silicate, Which'may be used with a large measure of confidence if cushioned as by a felt heat insulating foundation.`

The principles of construction above generally outlined are illustrated in' the accompanying drawings, in Which:-

Fig. l is a vertical section representing a typical application of the invention to an oil storage tank having la plate metal roof;

Fig. Q'is a vertical section at one of the joints between the roof plates; and

FigfB is a detail vertical section at one of' the joints between adjacent sheets of insulation material.

The tank siding 1 has, as usual, an eaveangle iron 3, on which rests the roof' plate 2. The major part of the tank roof'is covered with sheets of heat insulating felt l?, a. material which, as an incident to its interstitial structure and constituent interJ laced fibres, is marked degree.

The weather-proofing covering," in the preferred construction here shown, consists of two layers (preferably each of double or triple lamination) 21 and 22 of `asbestos roofing felt or paper, each layer being impregnated lwith'asphaltic material at one side, and 4having alight colored,lh"eat rey unimpregnated layer on the other ecting,

ins ummpregnated layer 1s `bibulous side.

yielding and elastic to a `the heat insulating material.

or absorbent, and thus Well adapted to unite with a liquid cementitious material.

In theV preferred form ol tank covering here shown, by which a large measure of insurance against vapor' percolation is provided, the tank roof plating is'irst coated with a base layer e of substantial thickness.n say 1/8 inch-oi2 .ncrmally elastic, petro- `leum-vaporresistadtl cement, such as the typical glue-glycerine composition above mentioned, this coating, laid oriiovved on while hot, being built up andismoothed. over the laps and rivets, as at la (Fig. 2) so as to provide acont-inuous smooth surface, free .of ,porous material such as paper (red resin paper is Well adapted to the purpose) well coated on both sides with vapor-proof cement, and thereby adhesively secured yto the base layer of similar cement, is recoin mended.

y Over the primary vapor-sealing layer of cement, or cement and Vapor-proofed inembrane, there is laid the heat insulating covering 17 this being a thick felt ot any approved fibrous material or mixture, such as cattle hair, asbestos fibre, Wood or other vegetable fibres, wool, etc. This felt should be laid on the vapor-proof cement layers, or the superposed cement coated membrane While the cementitious material is sui/E ciently fluid to be enmeshed in the surface of the felt, which is thus, adhesively secured to the material beneath it, and to the roeir of the tank.r Points between adj accnt sheets of the felt layer 17 may be covered by strips u 1S (Fig. 3) of heavy paper, or cloth, preferably Well coated and impregnated with vapor-proof cement.

.Vhen the heat insulating layer i7 is in place, 'a coating of vapor-proof cement is spread upon it, covering the sheets strips 18. This coating, if not too freely luid,may be flowed upon the porous heat insulating material and will be held in the. superficial region thereof without undue penetration into its body, forming acontinuous pellicle. O r, the vapor-proof cement ma be first applied to porous sheets in a .thick layer and these vsheets laid upon The layer marked 20 in the drawings represents this covering pellicle of vapor-proof cement. in either/form. l

The preferred Weatherproof top covering consistsof tivo layers4 of asbestos paper or felt, impregnated with asphalt from one and joint llayer 20, to which,

side, the lamina of paper at th'e other side being adhesively secured to the impregnated laminas by means of the asphalt, but left for the most part unimpregnated, so. that it remains in a bibulous or absorbent condi tion. x Onesuch multiple or laminated sheet (21) is laid with its absorbent face down, and resting on the vapor-proof, cement by the application ot heat, or merely by-pressure contact, it is made to adhere. is then laid with its asphalted surface down, upon the exposed asphalted surface 'of the sheet 9.1, hot asphalt being mopped on during the process, as is usual in the assembling of asphalted asbestos roofing sheets.

The same principles of construction as above described'in respect to the major portion of the tank top hold good for the special covering construction required for the periphery of the tank top. An inner seal is made at the edge of the tank top by applying strips of fabric or felt or paper, Well coated on both sides with the vaponproot cement, these strips (i, being adhesively applied to the upper side of the tank cover 2 near the rim thereof, carried over the rim and the supporting angle irons 3, and laid against the tank side 1, to which these strips adhere. The inner sealing strip 6 (Fig. 1) is shown as Wrapped closely over the rim of the tank cover 2 and adhesively attached to the eaves angle 3; it may, however, be allowed to hang unattached to the angle 3, so as to provide'slack to be taken up if the tank top should shift outwardly in relation to the tank side.

Eave strips 7, of sheet material, metal, mill board, etc., are laid over the sealing strips 6, and project radially so as to ali'ord support for the outer aling covering and hold it spaced slightly from the periphery of the tank top itself.

The outer sealing covering. comprises heat insulating felt layers 12 and 13 to which are cemented paper or other flexible sheets 9 and 14, each thoroughly coated on both sides with the vapor-proof elastic cement. For further protection of this outer seal, a sheet 8 of asphalt-impregnated cloth, felt, or asbestos paper is laid on, and cemented to, the vapor-proofed membrane 9.

This Icomposite protective covering is lapped over the lower edge of the inner seal 6, and firmly bound to the tank side by means ot Wire cable ties 15 and 8, which embrace the entire periphery ot the tank side and may be set tig it by means of turnbuckles. Then the composite covering is folded upward and over the edge of the tank top. Preferably, the felt layer l?) is so proportioned as to project Withinthe layer 1.2, and the vapor-proof membrane 14 likewise made so as to project inward upon `the tan tops. Gusset strips 16 ot tapered section,

, The other roofing sheet Q2 composed preferably ol heat-insulating telt, may be laid inside the layers 13, so as to form therewith an even-surfaced base over Whichtolap the first course of the telt covering 1T. lt will be found .advisableto spread -a layer of the vapor-prooi1 over the eaves strips 7 surface ot the tank top before the outerl eaves seal is folded into place, so that the cemented membrane 10 may be iyellserured. This nnnnbrane may. be butted against or ,lappedr under the similar membrancd, it such be used.

The cement layer 20, either as a skin oi vapor-prooi cement or as a cemented ineinbrane, 'with Weather-proofing sheets 2l and 22, will be laid to or lapped over. the outer coverings of the telt sheets 1Q. 13.

l claim:-

A1. The combinatiom with the roof ot' an oil tank or like structure. liable to appreciable distortionunder temperature varia-Y tions. ot a covering comprising an elastic folted heat insulating layer overlying said roof, andan oil-vapor proof layer overlying said 4lielted layer, the fclted layer serving as a cushion to reduce the eti'ect ol distortions ot the root on the vapor-prooi layer.

rlhe combination, with the root of an oil tank or like structure., liable toappreci able distortions under temperature varia.- tions. ot a covering comprising an elastic feltcd heat insulating layer overlying said roof, and an oil-vapor prooi' layer overlying said felted layer, the felted layer serving as a cushion to reduce the effect of distort-ions of the roof on the vapor-proof layer. and a Weather proof layeroverlying `said vapor proof layer to protect the latter against disintegration by water.

3. The combination, with the root of an oil tank or like structure,v liable to appreciable distortion under temperature varia-- tions, of a covering comprising an elastic elted heat insulating layer overlying said roof, and an elastic oil-vapor proof layer overlying said felted layer, the felted layer serving as a cushion to reduce the eliiect of distortions of the roof' on the uapor-proof layer.

4c. The combination, With the roof of an oil tank or like strnctiire, able distortion under temperature variations, of a covering comprisingr an elastic elted heat insulating layer overlying said rooi"` and an elastic oil-,vapor proof layer overlying said elted layer, the lielted layer serving as a cushion to reduce the eil'ect of distortions of t-he root on the vapor-proof layer, and a Weather proof layer overlying said vapor proof layer to protect the latter against disintegration by water.

The combination,

l tank or like. structure, liable to appreci-l able distortion under temperature variacement and the adjoiningv liable to appreeiwith the roof of an tions, ot a. covering comprising an elastic oil-vapo?. proof layer overlying the roof, an elastic elted heat insulating layer overlying said vapor proof layenemd a second oil vapor proo't layer overlying said felted layer, the elted layer serving as a cushion to reduce the effect of distortions of the roof on the vapor proof layer overlying it.

"6. The combination, with the roof of an oil tank or like structure, liable to appreciable distortion under temperature veriations7 o" covering comprising :in elastic oilvnpor proof layer overlying the roof,v an

' Lesmo@ elastic felted heat insulating layer overlying said vapor proof layer, and a second oil vapor proof layer overlying said felted layer, the elted layer serving as a cushion to reduce 'the effect of distortions of the roof on the vapor proof layer overlying it, and a Weather proof layer overlying said vapor proof layer to protect the latter against disintegration by Water.

Signed by me at St. Louis, Missouri this eighth day of May 1925. l

LESLIE A. BALDWN." 

